The present invention relates to the emission of pulsed energy and it relates especially, though not exclusively, to an electrical drive circuit for causing a laser device to emit well defined pulses of infra-red energy.
A requirement for such a drive circuit exists, for example, in the field of high resolution range finding, where semi-conductor devices are used to trigger the laser device. It is necessary to apply such a high current to the laser device that the current has to be shared amongst a plurality of the semi-conductor devices but, if this is done, a problem occurs because the triggering pulse, which should be of well defined shape and of a short duration, such as around ten nanoseconds or more, tends to be degraded because different devices have different characteristics.
It has been proposed to attack this problem by individual adjustment of the operating voltages applied to the various devices. This, however, is undesirable in practice and it is an object of this invention to provide a different, and more satisfactory, technique for overcoming or reducing the aforementioned problem.